Purdue University creates new method to drive fuel cells for portable electronics

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Purdue University creates new method to drive fuel cells for portable electronics

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September 1, 2005 Engineers at Purdue University have developed a new way of producing hydrogen for fuel cells to automatically recharge batteries in portable electronics, such as notebook computers, and eliminate the need to use a wall outlet. The findings were presented last Sunday (August 28) during the annual meeting of the American Chemical Society in Washington, D.C., and also will be detailed in a peer-reviewed paper to appear in an upcoming issue of the journal Combustion and Flame.

The paper was written by research scientist Evgeny Shafirovich, postdoctoral research associate Victor Diakov and Arvind Varma, the R. Games Slayter, Distinguished Professor of Chemical Engineering and head of Purdue's School of Chemical Engineering.

The researchers developed the new method earlier this year and envision a future system in which pellets of hydrogen-releasing material would be contained in disposable credit-card-size cartridges. Once the pellets were used up, a new cartridge would be inserted into devices such as cell phones, personal digital assistants, notebook computers, digital cameras, handheld medical diagnostic devices and defibrillators.

The method also might have military applications in portable electronics for soldiers and for equipment in spacecraft and submarines, Varma said.

The new technique combines two previously known methods for producing hydrogen. The previous methods have limitations making them impractical when used alone, but those drawbacks are overcome when the methods are combined, Varma said.

One of the methods was invented by Herbert C. Brown, a chemist and Nobel laureate from Purdue who discovered a compound called sodium borohydride during World War II. The compound contains sodium, boron and hydrogen. He later developed a technique for producing hydrogen by combining sodium borohydride with water and a catalyst. The method, however, has a major drawback because it requires expensive catalysts such as ruthenium.

The other method involves a chemical reaction in which tiny particles of aluminum are combined with water in such a way that the aluminum ignites, releasing hydrogen during the combustion process. This method does not require an expensive catalyst, but it yields insufficient quantities of hydrogen to be practical for fuel cell applications.

"Our solution is to combine both methods by using what we call a triple borohydride-metal-water mixture, which does not require a catalyst and has a high enough hydrogen yield to make the method promising for fuel cell applications," Varma said. "So far we have shown in experiments that we can convert 6.7 percent of the mixture to hydrogen, which means that for every 100 grams of mixture we can produce nearly 7 grams of hydrogen, and that yield is already better than alternative methods on the market."

The researchers have filed a provisional patent application for the technique and hope to increase the yield to about 10 percent through additional experiments, Shafirovich said.

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